214 THREE CRUISES OF THE “ BLAKE.” 
glands, and Vogt regarded the yellow cells of Velella (Figs. 
137, 137 nats and Porpita as liver cells. 
In 1871 Cienkowsky expressed the 
opinion that these yellow cells were para- 
sitic algæ, basing his view on the fact 
that they survive the radiolarians, mul- 
tiply, and become encysted, — pheno- 
mena not in the least connected with 
the life process of radiolarians. In 1879 
Hertwig discovered similar cells in acti- 
Fig. 187. — Velella mutica, Dl which he considered as unicellular 
Vascular canal filled with yel- algze. 
еа REE Tn 1881 Dr. Brandt confirmed Cien- 
kowsky’s discoveries, and strongly urged the para- 
sitic nature of the cells. Geddes subsequently con- 
firmed the views of Cienkowsky and Brandt, and 
traced the presence of starch and of a cell wall 
of true plant cellulose; he showed also that the 
chemical composition and the mode of division of FS ж ДЕТ 
these yellow cells were those of unicellular айо, relat ae 
for which he proposed the name of Philozoón. The exposure 
of large quantities of radiolarians soon proved them to be stud- 
ded with tiny gas globules, and a shoal of Velelle yielded 
large quantity of gas containing more than twenty-one per cent 
of oxygen. Dr. Geza Entz seems to have anticipated, as early 
as 1876, the observations and theoretical deductions of both 
Brandt and Geddes. 
In the relationship of these animals and plants, — for which 
the name of S; ymbiosis, g given by De Bary to an association of 
dissimilar organisms, has pw adopted, — it cannot be doubted 
that the animal cell must be benefited by the death of the 
vegetable cells which are digested, and that the animal cell is 
constantly producing carbonic acid and nitrogenous waste, 
which are of the first importance to the vegetable cell; the 
vegetable cell in its turn evolving oxygen tiden the uvm 
of sunlight, which is taken up by the surrounding animal 
tissues. 
This association, as far as we know, must be very beneficial, for 
